Although reconstructive surgery has become more sophisticated, surgeons are still limited by the quality of the host tissues in patients who have received radiation therapy. Therapeutic administration of radiation therapy results in a chronically injured tissue bed which is poorly perfused and there is an inability of the local tissues to revascularize flaps and grafts. Attempts to improve vascularization with hyperbaric oxygen have met with only limited success and seem to be an indirect method of treating the problem. This study is a pilot project to determine if the injection of an angiogenic agent can restore a significant amount of the vascularity to a chronically injured irradiated tissue. A chronic radiation injury will be created on the lateral thigh region of laboratory animals (rats). The effect of intradermal injection of a known angiogenic agent (a degradation product of hyaluronic acid) will be determined by quantifying changes in the local vascularity of the irradiated field. The change in vascularity will be quantified by injection of microspheres labeled with Co-57 as well as by microangiograms of the irradiated fields.